Archaeoastronomy
Archaeoastronomy (also spelled archeoastronomy) is the study of ancient or traditional astronomies in their cultural context, utilizing archaeological and anthropological evidence. The anthropological study of astronomical practices in contemporary societies is often called ethnoastronomy, although there is no consensus as to whether ethnoastronomy is a separate discipline or is a part of archaeoastronomy. Archaeoastronomy is also closely associated with , the use of historical records of heavenly events to answer astronomical problems and the , which uses written records to evaluate past astronomical traditions. It is most frequently mentioned with astronomical claims regarding or the . History of archaeoastronomy Archaeoastronomy is almost as old as archaeology itself. Heinrich Nissen was arguably the first archaeoastronomer, publishing Das Templum: Antiquarische Untersuchungen in 1869. Other researchers followed. The astronomer was active at the end of the nineteenth century and the start of the . His studies included an examinations of Egyptian temples in The Dawn of Astronomy in 1894 and of Stonehenge published as Stonehenge and Other British Stone Monuments Astronomically Considered in 1906. The archaeologist published extensively in the on the astronomical alignment of s in the in the same period. Archaeoastronomy was, for a while, a respectable subject. The first issue of the archaeological journal , published in 1927, includes an article on archaeoastronomical research.A.P. Trotter, Stonehenge as an Astronomical Instrument, Vol 1:1, 1927, 42–53 In the interest in archaeoastronomy waned until the 1960s when the astronomer proposed that Stonehenge was a computer. Around the same time the engineer published his survey results of ic sites also proposed widespread practice of accurate astronomy in the British Isles. The claims of Hawkins were largely dismissed. , Moonshine on Stonehenge, Vol 49:159, 1966, 212–6 However, Thom’s analysis continued to pose a problem. A re-evaluation of Thom’s fieldwork by Clive Ruggles attempted to show that his claims of high accuracy astronomy were not fully supported by the evidence. Nevertheless there was evidence of widespread interest in astronomy associated with megalithic sites. The response from most archaeologists was tepid. Only one, Euan MacKie, recognised that Thom’s theories needed to be tested and he excavated at the Kintraw standing stone site in Argyllshire in 1970 and 1971 to check whether the latter’s prediction of an observation platform on the hill slope above the stone was correct. There was an artificial platform there and this apparent verification of Thom’s long alignment hypothesis (Kintraw was diagnosed as an accurate winter solstice site) led him to check Thom’s geometrical theories at the Cultoon stone circle in Islay, also with a positive result. MacKie therefore broadly accepted Thom’s conclusions and published new prehistories of Britain.E. MacKie, Science and Society in Prehistoric Britain, Paul Elek, 1977, ISBN 0-236-40041-X Until the early 1980s — with the exception just mentioned — most archaeoastronomical research in the United Kingdom was concerned with establishing the existence of astronomical alignments in prehistoric sites by means rather than the social practice of astronomy in ancient times. In the , anthropologists began to more fully consider the role of astronomy in societies. This approach had access to sources that the of Europe lacks such as M. Zeilik, The Ethnoastronomy of the Historic Pueblos, I: Calendrical Sun Watching, Archaeoastronomy No. 8 (Supplement to the Journal for the History of Astronomy), 1985, pp. S1–S24; The Ethnoastronomy of the Historic Pueblos, II: Moon Watching, Archaeoastronomy No. 10 (Supplement to the Journal for the History of Astronomy), 1986, pp. S1–S22. and the records of the early . This allowed New World archaeoastronomers to make claims for motives which in the Old World would have been mere speculation. The concentration on historical data led to some claims of high accuracy that were comparatively weak when compared to the statistically led investigations in Europe. This came to a head at a meeting sponsored by the in in 1981.C.L.N. Ruggles, Archaeoastronomy in the 1990s, Group D Publications. 1993, ix, ISBN 1-874152-01-2 The and research questions of the participants were considered so different that the conference proceedings were published as two volumes.A. F. Aveni (ed.), Archaeoastronomy in the New World: American Primitive Astronomy, , 1982, ISBN 0-521-24731-4; D. C. Heggie (ed.), Archaeoastronomy in the Old World, , 1982, ISBN 0-521-24734-9 Nevertheless the conference was considered a success in bringing researchers together and Oxford conferences have continued every four or five years at locations around the world. The subsequent conferences have resulted in a move to more interdisciplinary approaches with researchers aiming to combine the contextuality of archaeological research,A.F. Aveni, World Archaeoastronomy, , 1989, xi–xiii, ISBN 0-521-34180-9 which broadly describes the state of archaeoastronomy today. Rather than merely establishing the existence of ancient astronomies archaeoastronomers seek to explain why people would have an interest in the night sky. Methodology Because of the wide variety of evidence, which can include artefacts as well as sites there is no one way practise archaeoastronomy. Despite this it is accepted that Archaeoastronomy is not a discipline that sits in isolation. Because Archaeoastronomy is an interdisciplinary field, whatever is being investigated should make sense both archaeologically and astronomically. Studies are more likely to be considered sound if they use theoretical tools found in Archaeology like and and if they can demonstrate an understanding of found in Astronomy. Artifactual analysis In the case of artifacts such as the , alleged to be a Bronze Age artifact depicting the cosmos, the analysis would be similar to typical as used in other sub-disciplines in archaeology. An artifact is examined and attempts are made to draw analogies with historical or ethnographical records of other peoples. The more parallels that can be found, the more likely an explanation is to be accepted by other archaeologists. Another well-known artifact with an astronomical use is the . In this case analysis of the artifact, and reference to the description of similar devices described by Cicero, would indicate a plausible use for the device. The argument is bolstered by the presence of symbols on the mechanism, allowing the disc to be read. Symbolic analysis In some cases the use of an artefact may be known, but its meaning may not be fully understood. In such cases an examination of the symbolism on the artefact may be necessary. A mundane example is the presence of s found on some shoes and sandals from the Roman Empire. The use of shoes and sandals is well known, but Carol van Driel-Murray has proposed that astrological symbols etched onto sandals gave the footwear spiritual or medicinal meanings.C. van Driel-Murray, Regarding the Stars, TRAC 2001: Proceedings of the Eleventh Annual Theoretical Roman Archaeology Conference Glasgow 2001. eds. M Carruthers, C. van Driel-Murray, A. Gardner, J. Lucas, L. Revell and E. Swift. Oxbow Books. 2002, 96–103, ISBN 1-84217-075-9 This is supported through citation of other known uses of astrological symbols and their connection to medical practice and with the historical records of the time. More problematic are some s. Symbols on rock are one such class of symbol which are occasionally argued to posses astronomical meanings. An example is the Sun Dagger of which is a glint of sunlight passing over a spiral petroglyph. The location of the dagger on the petroglyph varies throughout the year. At the solstices a dagger can be seen either through the heart of the spiral or to either side of it. It is proposed that this petroglyph was created to mark these events. If no ethnographic nor historical data are found which can support this assertion then acceptance of the idea relies upon the reader’s own belief as to whether or not there are enough petroglyph sites in North America that such a correlation could occur by chance. It is helpful when petroglyphs are associated with existing peoples. This allows ethnoastronomers to question informants as to the meaning of such symbols. Alignment analysis The most public image of archaeoastronomy is the practice of alignment analysis. This is the study of the orientation of structures and calculating the direction in which they face. In the case of Stonehenge it is well known to face the rising midsummer sun. In the case of the pyramids of Egypt they face north, probably to face the circumpolar stars.K. Spence, Ancient Egyptian Chronoology and the astronomical orientation of the pyramids, , Vol 406, 16 November 2000, 320–324. The use of alignment analysis may vary depending upon the researcher. As a coarse stereotype archaeoastronomers from an historical background tend to have an idea which is then tested by examining structures for alignments. Astronomically-minded archaeoastronomers may analyze large numbers of sites and attempt to find statistical patterns. This approach was particularly employed in early papers by pioneers in the field such as who conducted extensive fieldwork at megalithic sites and concluded many sites were situated to observe the moon. In this instance the aim was to prove that there is an astronomical problem which requires an historical explanation. This latter approach continues to an extent in some modern research but it has comparatively little direct impact on mainstream archaeology. One reason the statistically-led approach has proven unpopular with archaeologists and anthropologists was stated by the anthropologist Keith Kintigh: Recent statistically led research has tended to be more discriminating, choosing archaeologically associated sites and where possible referring back to historical or ethnographic records to place the findings in a social context. An alignment calculated by measuring the , the angle from north, of the structure and the altitude of the horizon it faces. The azimuth is usually measured using a or a . A compass is easier to use, though the deviation of the Earth’s magnetic field from true north, known as its must be taken into account. Compasses are also unreliable in areas prone to magnetic interference, such as sites being supported by scaffolding. Additionally a compass can only measure the azimuth to a precision of a half a degree.[http://www.brunton.com/manuals/current/Compasses/Transit.pdf Brunton Pocket Transit Instruction Manual, p. 22] A thedolite can be considerably more accurate if used correctly, but it is also considerably more difficult to use correctly. There is no inherent way to align a theodolite with North and so the scale has to be using astronomical observation, usually the position of the Sun. Because the position of celestial bodies changes with the time of day due to the Earth’s rotation, the time of these calibration observations must be accurately known, else there will be a systematic error in the measurements. If one is measuring buildings which were unlikely to be orientated by their builders to within fractions of a degree then a thedolite can be more trouble than it is worth. Horizon altitudes can be measured with a theodolite or a . Recreating the ancient sky Once the researcher has data to test, it is often necessary to attempt to recreate ancient sky conditions to place the data in its historical environment. Declination To calculate what astronomical features a structure faced a coordinate system is needed. The stars provide such a system. If you were to go outside on a clear night you would observe the stars spinning around the celestial pole. This point is +90° if you are watching the North Celestial Pole or −90° if you are observing the Southern Celestial Pole. The concentric circles the stars trace out are lines of celestial latitude, known as declination. The arc connecting the points on the horizon due East and due West (if the horizon is flat) and all points midway between the Celestial Poles is the Celestial Equator which has a declination of 0°. The visible declinations vary depending where you are on the globe. Only an observer on the North Pole of Earth would be unable to see any stars from the Southern Celestial Hemisphere at night (see diagram below). Once a declination has been found for the point on the horizon that a building faces it is then possible to say if a specific body can be seen in that direction. Solar positioning While the stars are fixed to their declinations the Sun is not. The rising point of the Sun varies throughout the year. It swings between two limits marked by the solstices a bit like a , slowing as it reaches the extremes, but passing rapidly through the mid-point. If an archaeoastronomer can calculate from the azimuth and horizon height that a site was built to view a declination of +23.5° then he need not wait until to confirm the site does indeed face the summer solstice. For more information see . Lunar positioning The Moon’s appearance is considerably more complex. Its motion, like the Sun, is between two limits — known as luna''stices rather than ''sol''stices. However, its travel between lunastices is considerably faster. It takes a to complete its cycle rather than the year long trek of the Sun. This is further complicated as the lunastices marking the limits of the Moon’s movement move on . For slightly over nine years the extreme limits of the moon are outside the range of sunrise. For the remaining half of the cycle the Moon never exceeds the limits of the range of sunrise. However, much lunar observation was concerned with the '' of the Moon. The cycle from one to the next runs on an entirely different cycle, the . Thus when examining sites for lunar significance the data can appear sparse due the extremely variable nature of the moon. See for more details. Stellar positioning Finally there is often a need to correct for the apparent movement of the stars. On the timescale of human civilisation the stars have maintained the same position relative to each other. Each night they appear to rotate around the celestial poles due to the Earth’s rotation about its axis. However, the Earth spins rather like a . Not only does the Earth rotate, it wobbles. The Earth’s axis takes around 25700 years to complete one full wobble. The effect to the archaeoastronomer is that stars did not rise over the horizon in the past in the same places as they do today. Nor did the stars rotate around as they do now. In the case of the , it has been shown they were aligned towards , a faint star in the constellation of . The effect can be substanstial over relatively short lengths of time, historically speaking. For instance a person born on December 25 in Roman times would have been born under the astrological sign of . In the modern period a person born on the same date is now a Astrological Things What is Your Sign, Really ? due to the precession of the equinoxes. Transient phenomena Additionally there are often transient phenomena, events which do not happen on an annual cycle. Most predictable are events like s. In the case of s these can be used to date events in the past. A solar eclipse mentioned by enables us to date a battle between the and the , which following the eclipse failed to happen, to May 28, 585 BC.Herodotus, The Histories, I.74 Other easily calculated events are whose remains are visible to astronomers and therefore their positions and magnitude can be accurately calculated. Some s are predictable, most famously . Yet as a class of object they remain unpredictable and can appear at any time. Some have extremely lengthy s which means their past appearances and returns cannot be predicted. Others may have only ever passed through the solar system once and so are inherently unpredictable. s should be predictable, but the s are cometary debris and so require calculations of orbits which are currently impossible to complete. Other events noted by ancients include , s and s all of which are as impossible to predict as the ancient weather, but nevertheless may have been considered important phenomena. Major topics of archaeoastronomical research The use of calendars A common justification for the need for astronomy is the need to develop an accurate for reasons. Ancient texts like ’s Works and Days, an ancient farming manual, would appear to contradict this. Instead astronomical observations are used in combination with signs, such as s to determine the seasons. Ethnoastronomical work with the of shows that haphazard astronomy continued until recent times in some parts of the world.D. Turton and C.L.N. Ruggles, Agreeing to Disagree: The Measurement of Duration in a Southwestern Ethiopian Community, Current Anthropology Vol. 19.3, 1978, 585–600 All the same, calendars appear to be an almost universal phenomenon in societies as they provide tools for the regulation of communal activities. An example of a non-agricultural calendar is the Mayan Tzolkin which is a cycle of 260 days. This count is based on an earlier calendar and is found throughout Mesoamerica. This formed part of a more comprehensive Maya Calendar which combined a series of astronomical observations and ritual cycles.A.F. Aveni, Empires of Time, Basic Books, 1989, ISBN 0-465-01950-1 Other peculiar calendars include ancient . These were nominally , starting with the . In reality the calendar could paused or days skipped with confused citizens inscribing dates by both the civic calendar and ton theoi, by the .S. McCluskey, The Inconstant Moon: Lunar Astronomies in Different Cultures, Archaeoastronomy: The Journal of Astronomy in Culture Vol 15. 2000, 14–31 The lack of any universal calendar for ancient Greece suggests that coordination of panhellenic events such as or rituals could be difficult and that astronomical symbolism may have been used as a politically neutral form of timekeeping.A. Salt and E. Boutsikas, Knowing when to consult the oracle at Delphi. Vol 79:305, 2005, 562–72 Myth and cosmology Another motive for studying the is to understand and explain the . In pre-scientific times was a tool for achieving this and the explanations, while not , are . The s arranged their empire to demonstrate their cosmology. The capital, , was at the centre of the empire and connected to it by means of ceques, conceptually straight lines radiating out from the centre.B. Bauer and D. Dearborn, Astronomy and empire in the ancient Andes: the cultural origins of Inca sky watching, University of Texas, 1995, ISBN 0-292-70837-8 These ceques connected the centre of the empire to the four suyus, which were regions defined by their direction from Cusco. The notion of a quartered cosmos is common across the . Gary Urton, who has conducted fieldwork in the Andean villagers of Misminay, has connected this quartering with the appearance of the in the night sky.G. Urton, At the crossroads of the earth and the sky: an Andean cosmology, University of Texas. 1981, ISBN 0-292-70349-X In one season it will bisect the sky and in another bisect it in a fashion. The importance of observing cosmological factors is also seen on the other side of the world. The in is laid out to follow cosmic order though rather than observing four directions the Chinese saw five, , , , and . The Forbidden City occupied the centre of ancient Beijing. , Skywatchers, Shamans and Kings, John Wiley and Sons, 1997, 196–9, ISBN 0-471-32975-4 One approaches the Emperor from the south, thus placing him in front of the . This creates the situation of the heavens revolving around the person of the Emperor. The Chinese cosmology is now better known through its export as . There is also much information about how the universe was thought to work stored in the mythology of the s. The Barasana of the plan part of their annual cycle based on observation of the stars. When their constellation of the Caterpillar-Jaguar falls they prepare to catch the pupating caterpillars of the forest as they fall from the trees.M. Hoskin, The Cambridge Concise History of Astronomy, , 1999, 15–6, ISBN 0-521-57600-8 This provides planning for food procurement at a time when hunger could otherwise be a problem. A more well-known source of constellation myth are the texts of the Greeks and Romans. The origin of their constellations remains a matter of continuing and occasionally fractious debate. Displays of power * Category:Archaeological sub-disciplines Category:Astrological factors Category:History of astronomy Category:Earth mysteries Category:Ancient mysteries